Bourdon tube variable resistance valve



1947. 5. I. BILYEU BOURBON TUBE VARIABLE RESISTANCE VALVE Filed Oct. 20,1944 3 Sheets-Sheet l mvsmog Prald' I. B:

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@Zfd ATTOR 7 gig! Dec. 9, 1947. s. I. BJI YEU 2,432,082

' BOURBON TUBE VARIABLE RESISTANCE VALVE 7 Filed Oct. '20, 1944 sSheetZE-She'et 2 INVENTOR eraldf I. ,B (117mb 0 2 4 6 8 l0 [2 BY DIALINDICATION ATIORN Dec. 9, 1947. G, B LYE'U 2,432,082

BOURBON TUBE. VARIABLBRESISTANCE VALVE Filed Oct. 20, 1944 sSheets-Sheet s 25 68 70 I t 68 I lla i l!!!11142 51: kllllllll\\\\\.\\\\k\\\= I 55 2 E 419 52 57 48 if. 5/ 59 L Y INVENTOR Zelrald1.1311 6 BY 2 1? Q ATTSRN s 1 embodiment of theinvention; a: 7 Figure 3represents wgraohicallyz fluid flow l through the restrictor. asplottedagainst; incre-i ments'of dial setting; r -f p I a "Figure 4-"isan ielevationalsview :ot; a variable fluid restrictor embodyinggtheinvention;v Figure 5eisnaeside elevatlonalsview O i iineie-iiof FigurePatented Dec 9, 1947 1 This invention-relates to apparatus for provid-ZQJBOURDONTUBE VARIABLE sssisssses ing= ariadgustable restriction; to,theflow o; fluid 2 for automatic controllers,@andsmore particular ytoapparatusior. providing acouratejlow-restrict ing orfidwpassing.characteristics: 3'

Needle valves have in the past-been usedwas mechanism for providing.smalL; adjustable flows ofgasor iiquidsmButasucl'i valves have manydisadvantages =when :usedtin automatic controller's, towitztheirstufiing glandsare subject to is disadvantageous;ltliisproblemisserious; Fur.- ther, where it is desirable" to have:sseveralflowresisting'mechanisms' adjusted simultaneously to providefor flows' l'iaving"predetermined relationil0 leakage toatmosphereand=.when suchleakage ships; needle valves areunsatisfactorybecause of"their calibration diflicu'lties and a for other me- ;chanicalr'ea'sons. It'is' an 'ob'je'ct "of the-present invention-to pro- *i'iicie a' flow restricting device iWhjCh isnot subject -Yto thedisadvantages above-mentioned, and which may beadiusted to provideaccurate predetermined flow characteristics. i *It is-another obiect ofthe invention to provide an adjustable" restrictive device capable ofbeing used ior inany of the "same applications as here- 't'ofore havebeen furnished with needle valves, f but including; characteristics: andstructural feaenre's rendering it-superior-:in'1many5rconditions of1operatifcm' and in ease ofadjustment 0, needle 'va ves.- 1. saw;

" These and 'other objects of the mana e an 'be' in part pointed'out Iiro'mthe tent? l and will be innpart obvious l Theinvention,-accordingly. asses arise feetures ofconstruction;combinationsof elements,

" andarrang'ements of parts as will be exemplified in the structure tobe hereinafter more fu ly described and the scope ofit'healppllcation ofwhich will beset' forth' in the accompanying claims.

1* lathe-accompanying drawings, in which sevralembodiinentsof theinventionare shown;

gure 'l 'is a-geometrical diagram to be'used m theexplana'tionoftheinv'ention;

v mgure e :is a; schematic perspective. view of L an:strictorshowninFieure g: Figu e 6 152a; sectionalgview-takenvalong theV Geraldi liiiyeus-Foirboro, Mass; 'assignor top'lfhe Foxboronqompfrlnyg'Foxborol Mass j a corpora' ionjfof iltiassachusetts I r spplication October 20; 1944, serial. no. tsetse" new . [Fi ure 7g is aview o f;another embodiment oi theuinvention show'inghow tworestricto'rs' may be combined in a dualcapacity;

' Figure 8 a view takenalong the irregular line 8- 8 of Figure '7 iguresis n endelevation or the dual re Y stricter shown in Figures 7 'and'B;and

e re i oj'shows structure for effecting an adjustmest in a dualr'estrictor 01/ the type illustrated in'Figures 7-9.

.I'h'e invention in its preferred form makes use section cut fromordinary Bourdon tubing." Variations,in"thej restricting effect uponfluid flow therethrough may'be brought about by increasing or'decreasing' the radius of curvature of the section of tubing. ":Ihus.decreasing the radius of curvature decreases the cross-sectional area Asthe t ubing is bent more and morethe flow of .fluid through it foragiven pressure drop across .the tubing may be very nearlyreduced tozero.

:AS the tubing is unbent. the same pressure drop will produce arelatively larger fluid flow because res id flow ,therethrough is substa ly-reduced, a

s I It has been. discoveredfthatby bending such tubing inf'a certainmanner a highly advantageous ,seieeonsn s er "chzjanigefofv fluid flowto change fltubingto obtain 'variable'flow of" fluid there- 7 throughwhen operatedin said certain manner, a as will be described; has manyadvantages. Not

on y may thfiuidflow e easily adjusted and the calibration of the flowper degree ofvbending for a given tube remains with precision, but alsoconstant under conditions that would interfere with the effectiveresistances which might be obbeen discovered'between a change in thebending tained bythe use of needle valves.

1 The above mentioned relationship that has I of the tube and the flowthrough it is one that v z bending throughout the gives an equalpercentage change in'the flow through'the tubing for! an equalincrements of entire operative range of bendingo'f the tube. Such'arelationship has definite advantages in many industrial applications forit gives what'might be termed'a straight '1 line relationship betweenchange of restrictor setting to change of flow. 'This'relationship may"be"convenientlygiliustrated by an example. As-

surnelthat the .tub'e'is bent in equal steps. Then as the degree ofbending is changed from one step to another; tlzie ilriw through thetubing is chapgedin equal percentage steps. Thus, if each an arcuatelyshaped. restrictor resembling a of thel passagethrough the tubing andvice versa.

of bndingmaybefobtained. The use of such 7 step produces a flowvariation of 10%, and at a certain step the flow is 10 units per minute,and the tube is unbent one step, then the flow will increase 10%, i. e.,from 10 units per minute to 11 units per minute.

Such an equal percentage flow variation for equal steps of bendingthroughout a given range rigidly fixing one end of the tube and causingthe movable end of the tube tomove along a path which very nearlyapproximates the path that it would follow if it were moving freely.

In Figure 1 there is graphically shown a procedure for approximating thepath of the free end of an arcuately bent restrictor tube to obtain therelationship above described for a selected range of tube bending. Thefixed end of the tube is located at point A. By construction, the radiusor the arc of the tube when bent exactly into a semi-circle (i. e., whenits free end B is at point Ba) has been takenas equal to the value R.The

length of the 180 arc of the tube correspondingly is equal to 1rR or/,;1rD, whereD is the diameter between the two ends of the tube when thetube subtends an arc of 180.

The tube is now assumed to be bent into different circular curvatures.Thus it is first assumed to be bent so that its length, which remainsunchanged, subtends 240 of arc, or of a circle. In this condition, theend B is at position B1 and the radius n of the arc of the tube has avalue of AB. This is obtained as follows: the length of the arc of thetube is KR. Hence, the length of the tube bent to the 240 of arc is 1rR.The length is also %X21rr1. Putting these equal to each other r1= /4R.Using this same procedure, when the tube is bent to 210 of are, or /m ofa circle, so that its end B is at position B2, its radius of curvaturerz=/1R; when bent to 180 of arc, or /z of a circle, its radius ofcurvature ra=R; when bent to 160 of arc, or /9 of a circle, its radiusof curvature r4=/aR; when bent to 140 of arc, or /1: of a circle, itsradius of curvature rs= /1R; and when bent to 120", or /3 01 a circle,its radius of curvature rc= /2R. The positions of the end B for the lastthree bending conditions are respectively B4, B5, Be. The centers of thecircles whose radii are r1, r2, r3, etc. are indicated respectively atC1, C2, C3, etc.

No arc of a circle can be drawn which will pass through all the pointsB1 through Ba, but a center P can be located for the circle passingthrough points B1; B2, and B3; or for a center for a circle passingthrough'points B2, B3, and B4, or for a center for a circle passingthrough points B3, B4, B5, etc. Thus the movement of the free end of thetube may be so restricted by mechanical ing all the points B obained asabove described. The closer points B1, Ba, Ba, etc. are locatedtogether, the more accurate will be the approximation of the path of themovable end of the tube to the portion of the true curve.

The next step in the construction is to select the limited range ofbending movement of the tube required to produce the flow variationsdesired. Such a selection depends upon such factors as the size of thetube and the range of flow variations that will be required. Having madesuch a selection, the center P about which the movable end of the tubeis to be located is selected. If, for example, the limited movement isto be from points Bl through Ba. the center P is located by theintersection of the two lines which respectively contain all the pointsequidistant from B1 and B2, and. from B: and B3. Or it'the limited rangeof movement of the movable end of the tube were to pass through pointsB3, B4, and Ba for example, then the center P about which the movableend of the tube is to pass is determined by intersection of the twolines which contain all the points equidistant from points B3, and B4,and from B4 and B5.

It is, therefore, apparent that the exact loca tion of the center P is amatter of engineering judgment to obtain the desired uniform bending ofthe tube throughout a limited selected range of bending to obtain thedesired equal percentage changes of fiow for equal changes in theposition of the movable end of the tube.

Figure 2 showsa restrictor, the design of which is based upon thediagram of Figure 1. The restrictor includes a gear sector 0 rotatableabout a fixed pivot P corresponding to center P selected as abovedescribed. Pivot P is formed by an arbor supported by a bracket 1secured with re-' spect to a base 2. Also secured to the base is one endof tube 3. The other end of tube 3 is attached to a block 4 pivotallysecured to gear sector 9 at point B. In order to locate both the fluidinlet and outlet in base 2, a flexible return tube 5 having no flowrestricting characteristics provides a return connection between block Iand base 2. Fluid is supplied through an inlet pipe I and base 2 intotube 3. Inside of block 4 there is a passage 4 connecting the free endor the tube with return tube 5 which, in turn, is connected at its otherend to an outlet plpel through base 2 to complete the circuit.- Sectorgear 9 pivots on arbor P and meshes with a worm I! on a shaft llrotatable by a hand knob I2. Thus, by .turnlng knob l2. the worm raisesor lowers sector 9 and makes the free end ofv the tube followapproximatel the same path which the free tube would inherently tend tofollow if it were caused to unbend over the same range of movement. l

Figure 3 illustrates graphically typical results that may be obtalnedwith avariable restrictor tube constructed as described above. Fluidflow values as indicated are plotted against the values given on thedial. The equation of the curve illustrated in Figure 3 has the generalform y=ce-'" where 11 represents flow, .1: represents dial setting, andc and m are constants which fit the equation to the platted curve. Thegraph means that the movable end of the tube is caused to passthroughpoints B1, B2, and B: as it moves.

shows pictorially one striking characteristic of the restrictor; namely,that for a given increment of change in dial setting, no matter where itoccurs on the scale, a corresponding percent change in fluid flowfollows which is in proportion to the increment of change in dialsetting: In other words, for a given change in dial setting a givenchange in percent of fluid flow resuits. This constant relationshipthroughout the range of the restrictor makes for easier and more rapidadjustment in thefleld.

Figures 4 and 5 show additional details of a restrictor mechanism. Thefluid enters through a supply pipe l4 which is held pressuretight withina stationary support block l5 by means of a screw Hi. It passes throughblock l5 and a. base block 42 (to be described) and through unrestrictedtubing ll soldered at points l8 and I9 to base block 42 and a movablesupport block 20. The, fluid then passes through block by means of anopening 2| (see Figure 4) into a tube 22 which is also soldered, atpoints 23 and 24, into blocks 20 and 42. Thereafter it passes throughblock 15 again and out an outlet pipe 25 which is held pressuretight bya screw 25.

A sector gear 21 is revolvable about a shoulder screw 28 mounted in abracket 29. Block 20 is fastened to the sector gear by means of a pin30. The gear and block are separated by a collar 3!. Sector gear 21 ismaintained in'proper engagement with a worm 32 by means of spacingwashers 33 and 34 (see Figure 4). Worm 32 is carried upon a shaft 35which, in turn; is supported within bracket 29 and a mounting plate 36.To the end of shaft 35 is secured a dial 3! and a knob 38. A pointer 39is secured to mounting plate 38 by means of a small screw 48. Rotationof knob 38 turnsthe worm which, in turn, rotates the sector gear toraise and lower support block 20 through the pin 30, thus flexing thetube and varying the resistance through the tube to the passage of fluidtherethrough.

Figure 6 is a cross-sectional view taken along the line 6-6 of Figure 4and shows the manner in which tube 22 is mounted upon support blocks l5and 42. Tube 22 is soldered to base block 42 at point 24. This baseblock fits tightly into a I groove Hz; in support block i5, and afluidtight gasket 45 is provided between the two blocks. The two blocksare held flrmly together by means of screws 46 and 41. Outlet tube 25 isprovided I with a cone-shaped compression fitting 43 which is forcedtightly against a seat 44 by screw 28-, thus preventing leakage offluid. Support, block i5 is indicated as secured to mounting plate 36 bymeans of a screw 4i.

Figures 7, 8, and 9 portray a dual model of two synchronized variableresistance tubes for the regulating of fluid flow. One application whichsuggests itself where such a dual restrictor might be useful is inconnection with reset and derivative mechanisms of automatic controlapparatus. One such apparatus is the copending application of Clesson E.Mason, Serial No. 385,493, flied March 2'7, 1941; another is in theapplication of rial No. 482,157, filed April 7,1943. A resistance tube48 is soldered into a base block 49 at one end and into an adjustableblock 50 at the other end. Similarly, a resistance tube into a baseblock 52 and an adjustable block'53; Fluid is led to block 49 throu h aflexible tube 480. and from adjustable block 50 through a flexible tube48b. Fluid connections for blocks 52 and 53 have been omitted from thedrawings in order to simplify the showing. Fluid is led into base blroks49 and 52 separately, then through the resistance tubes, and then outthrough the adjustable blocks. This makes two separate circuits ofvariable flow resistance-for example,

one for reset and the other for derivative func- Base tions forautomatic control apparatus. blocks 49 and 52 are pivotally mounted on abar described and claimed in George A. Philbrick, Se-

5i is soldered;

BI is maintained in of the tubes ure 10) may be substituted for 6 54which is fastened to a bracket 55. Theyare rotatably held onto bar 54 bymeans of spring clips 58 and 51. Adjustable blocks 50 and 53 arepivotally mounted on bar J58 and are rotatably retained in place byspring clips 59 and 50. A shaft 81 is threaded toward its lower end, asviewed in Figures 7 and 8, and screws perpendicularly through bar 58atits mid point. Shaft osition within a frame 62 a bearing hole 63, andat its upper end by a bearing hole 64. It passes perpendicularly througha clearance hole in the mid point of bar 54. A small pinion 65 isfastened onto shaft 6| by a force fit, and a knob is fastened onto theshaft by means of a set screw 81. Pinion 55 meshes with gear teeth onthe peripher of a dial 58 which turns upon a shoulder screw 59 fastenedto frame 82. An index Iil'is securely fastened to frame 52. Thus, byturning knob 56, blocks ,49 and 50 as well as blocks 52 and 53 are movedeither nearer together or farther apart so as to compress or expand theresistance'tubes and the pivotal mounting of blocks 48, 50, 52, and 53assures that tubes 48 and 5| always maintain true arcs regardless of theadjustment. This action either slows down or speeds up the flow of fluidthrough the tubes, thereby controlling the fluid flow. Rotation of knob55 turns pinion 55 and dial 58. The dial is graduated and calibratedtoread in units of at its lower end by In order to synchronize the flowthrough each or to give them a predetermined ratio with respect to oneanother, a block 'H (see Figblock 49 shown in-Figure 'l. The end of tube48, shown in Figure 10, is fastened into a separate block 12in which theinlet pipe is located. This block is raised and lowered by turning amicrometer screw 13 threaded within block 1 l. Thus, for a given dialsetting and flow through the other tube, by adlusting micrometer screwI3, fluid flow through tube 48 may be synchronized or otherwiseadjusted. 1 I

The Figures 2 and 3 construction may also be constructed so as to mounttwo or more restrictors to be adjusted in' synchronism as .described inconnection with Figures 7-10. In this connection, several supportsvor.segments 21 of Figure 2.may b p pr vided, each to move the end ofits'restricton. T e segments may be made adjustable with respe t to eachother to set up the desired relation between the restrictors, and thendriven synchronously by a manually turned hand knob 38.

Restrictors of the advantages over conventional needle valves.Particularlyi' however, they are not so subject to clogging and pluggingbecause of dust and o l as are needle valves when set for small flows.Also,

I they maintain their calibration. Because of the easily be adjusted tothedesired values by turning a dial to the desired setting. Therestrictors are easily and economically made from appropriate lengths ofconventional Bourdon tubing.

As many possible embodiments may be made of the above invention and aschanges may be made in the embodiments described without departing fromthe scope thereof, it is to be understood that all matter herein setforth or shown in type described have several the accompanying drawingsis to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In fluid operated apparatus of the character described, thecombination including: an arcuately bent restrictor of Bourdon tubing01' the like, and means for adjustably alterting the radius of curvatureof the restrictor independently of the fluid pressure therein, to changethe internal cross-section of the restrictor and hence its resistance topassage of fluid therethrough; said apparatus being characterized by thefact that said ing one end support thereof through a predetermeans holdsone end of the restrictor rigid and 7 moves the other end alongsubstantially the same path that said end would follow if free tobendand unbend.

2. In fluid operated apparatus of the character described, thecombination including: an arouately bent, Bourdon-like section of tubingopen to fluid new at each'end, an arbor-mounted supporting member, meansfor rotating said member, one end of said section of tubing being fixed,the other end of said section of tubing being movable and secured tosaid member, and the arbor supporting said member being located at apoint P, which point is the center of a circle passing through threeadjacent positions that the movable end of said tubing would occupy itcaused to bend and unbend while free from said memher.

3. In fluid operated apparatus of the character described, thecombination including: an arcuately bent restrictor of Bourdon tubing orthe like,.

an end support for each end of the restrictor, and a motion impartingmechanism for positively moving one end support through a predeterminedpath with respect to the other end support; said predetermined pathbeing the path that the one end of the tubing would inherently tend tofollow with respect to the other end if the one end were whollyunrestricted in movement and were moved only by changes of pressure fromwithin.

4. The combination of claim 3 wherein the mechanism includes: pivotalmountings for each end support, whereby the ends of the restrictor arefree to rotate upon the pivotal mountings during relative movementthereof so that the retrictor may maintain its inherent curvateconfiguration.

5. The combination of claim 3 wherein the mechanism includes: an arborfixed with respect to said other end, and an arm pivotally carried, uponthe arbor; said one end of the restrictor being pivotally carried uponthe arm for movement through an arc centered at the arbor.

6. In fluid operated apparatus of the character described a plurality ofarcuately bent restrictors of Bourdon tubing or the like, an end supportfor each end of each restrictor, a motion imparting mechanism for eachrestrictor for positively mov- 60 2,177,128

mined path with respect to the other end support thereof, and a couplingbetween the mechanisms or two adjacent restrictors for synchronizing therelative movements thereof.

'7. A fluid operated apparatus of the character described for imposingan infinitely variable quantity of resistance to fluid flow into a fluidcircuit including: an arcuately bent restrictor of Bourdon tubing or thelike through which a regulated amount of fluid is to pass, a fixed fluidconnection block fixedly carrying one end of the retrictor, a movablefluid connection block movably carrying the other end of the restrictor,an adjustable finger piece and cooperating visible scale for makingmanual adjustments to the apparatus, a pivotally mounted lever rotatableabout an axis fixed with respect to the fixed connection block, themovable connection block being carried upon the pivotally mounted lever,mechanism for transferring finger piece adjustments to the pivotallymounted lever to adjust the position of the movable connection blockwith respect to the fixed connection block, and the axis for thepivotally mounted lever being at a point substantially equidistant fromthree positions which would be assumed inherently by the movableconnection block if the restrictor were unrestrained in movement andwere moved only by changes in pressure from within.

8. In fluid operated apparatus or the character described, thecombination including: a plurality of arcuately bent restrctors ofBourdon tubing or the like, an end support for each end of eachrestrictor, motion imparting mechanisms for positively moving one endsupport of each restrictor through a predetermined path with respect toits other end support, said predetermined path being in each instancethe path that the one end of the restrictor would inherently tend tofollow if the one end were wholly unrestrained in movement and weremoved only by changes in pressure from within, 'and said mechanismsincluding adjustment structure for selectively adjusting the radius ofcurvature of one restrictor with respect to the radius of curvature ofanother, whereby fluid flow through said one restrictor may beindividually regulated with respect to fluid flow through said other.

GERALD I. IBILYEU file of this patent:

UNITED STATES PATENTS Number Name Date 2,170,557 Guarnaschelli Aug, 22,1939 Johnson Oct. 24, 1939

